Artificial leg



Nov. 14, 1950 J. G. CATRANIS ARTIFICIAL LEG (DIAPHRAGM KNEE LOCK CONTROL) Filed Dec. 11, 194'? IN V EN TOR.

m I 1/ F7. A M M 6 lllllllllllll l Patented Nov. 14, 1950 UNITED STATES PATENT OFFICE ARTIFICIAL LEG (DIAPHRAGM KNEE LOCK CONTROL) John G. Catranis, Syracuse, N. Y.

Application December 11, 1947, Serial No. 791,129

6 Claims. (01. 3-3) This invention relates to artificial legs for above-the-knee amputees, which artificial leg includes a lower leg hinged to a stum receiving socket by a knee joint, and has for its object a control for the relative hinging action of the socket and the lower leg controlled by a slight axial action of the stump in its socket during the walking cycle creating differential pressures in a chamber in the socket below the stump, which pressures operate a diaphragm operating a knee lock.

It further has for its object a double check valve opening into the lower chamber of the socket below the stump for maintaining a predetermined partial vacuum in the chamber sufficient to hold the socket on the stump without creating an irritating drawing effect on the stump, and also maintaining a predetermined quantity of air in the chamber normally at less than atmospheric pressure and compressible to a predetermined pressure to operate or apply the knee look by relative endwise movement of the stump and the socket.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

Figure l is a fragmentary sectional view of the stump socket and lower leg hinged thereto showing the control for the knee lock.

Figure 2 is an enlarged diametrical sectional view of the valve for maintaining the air pressure in a chamber, within the socket below the stum at a predetermined minimum below normal atmospheric pressure.

The numeral l designates the socket which is of such shape as to snugly fit the stump of the amputee substantially in air tight relation, but permits a small amount of relative endwise or axial action due to the flexibility and resiliency of the muscles of the stump, without slipping at the periphery of the stump. The socket may be formed with an inwardly extending annular seat 2 on which the margin of the lower end face of the stump rests, with the end of the stump itself exposed in a closed chamber 3 in the socket below the lower end of the stump.

to the lower end of the socket. The movement at the knee joint is. in legs of this type, limited or 2 braked by so-called knee locks to prevent buckling of the knee during the walkingcycle. Insofar as this invention in concerned, the knee lock may be of any suitable or well known construction.

As here shown, it may be of the over-running roller clutch type including means for locking the rollers, or locking the over-running upon relative axial movement of the socket and stump toward each other to compress the airin the chamber 3. These types of knee locks include an operating or actuating member as 6. The operating or actuating member ishere shown as concentric with the axis 5 of the knee joint and as having a rocking movement into and out of position to lock the kne joint. The actuating or operating member 6 is controlled in various ways, and one of the features of this invention is a control for the actuating member 6.

The control here shown includes a pressure operated member within the socketand forming the bottom wall of the chamber 3. The pressure operated member here shown is a vibratable diaphragm I located in the socket I above the knee joint. A predetermined partial vacuum is maintained in the chamber 3 and not only serves to hold the socket on the stump of the amputee, but also toinitially deflect the diaphragm upward due to the atmospheric pressure on the lower side of the diaphragm. The normal deflection may be opposed or neutralized by a spring hereinafter referred to. There is relative axial movement'of the socket and the stump when the socket is placed on the stump, or the stump inserted into the socket. Also, when the amputee lifts the straightened leg and foot off the walking surface, or takes his weight off the straightened leg, and when he again applies his weight to the leg. As the weight of the amputee is applied to the stump during the walking cycle, the stump compresses the air in the partial vacuum in the chamber 3, and the diaphragm 1 is deflected downward locking the knee lock. When the Weight is removed from the stump, the

original vacuum is restored, and the diaphragm knee joint. The normal or operating vacuum in the chamber 3 is maintained by the check valving to be described. The downward flexing of the diaphragm l operates the operating member or actuator 6 of the knee lock to apply a braking or locking action to the knee joint. The release of such pressure operates to release the knee joint. The motion of the diaphragm is transferred to the operating member of the knee joint through motion transmitting means here shown as a lever B pivoted at one end at 9 to a fixed point within the socket i below the diaphragm, and at its other end located to be thrust against by the diaphragm, a second lever, as an angle lever 13 pivoted below the lever 8 within the socket and having one arm connected by a link I! to the lever 8, and its other arm connected by a link l2 to a radial arm [3 on the operating member 6.

As here shown, the lever 8 extends radially relatively to the diaphragm l, which is discoidal and fixed at its rim, and is pivoted at M to a thrust member l5 secured to the diaphragm at the center thereof. A spring l6, acting to pull the lever downward serves to operate the lever 8 to lock the knee lock before the leg is applied to the stump and after it is removed therefrom. The spring l6 acts against the action of the atmospheric pressure on the diaphragm inresponse to vacuum in the chamber 3 created by upward movement of the stump in the socket or downward movement of the socket relative to the stump.

In operation, as the stump during its muscular action shifts downwardly when the weight of the amputeefs body is applied thereto, the air in the chamber 3 is compressed, deflecting the diaphragm lndownward, and the motion is transferred to the knee lock to operate it to brake or lock the knee joint through the levers 8 and Hi,

motion transmitting levers and linkage return therewith to their starting position, thus again operating the knee lock member 3 to release the knee joint of the locking effect.

For instance, upon lifting the stump to lift the foot off the walking surface, the socket may shift downward due to the flexibility of the stump muscles or flesh on the stump, thus enlarging the ehamber 3 and creating additional space or vacuum therein sufiicient to permit the outside atmospheric pressure on the diaphragm to overcome the vacuum and the force of the spring l6 and unlock the knee lock to permit the leg to bend at the knee joint. This occurs when the other or natural leg is carrying the weight of the amputee in taking a step forward on the natural leg and the artificial leg is extended rearward. Hence, the artificial leg, so flexed at the knee joint, can swing forward at the knee joint while swinging forward about the hip joint in taking a step forward with the artificial leg. When the foot, or the heel thereof, is pressed on the walking surface relative axial movement of the socket and stump occurs and the air is compressed in the chamber 3 to a point where the pressure in the chamber 3, plus the force of the spring 15, overcomes the outside atmospheric pressure on the diaphragm and operates the knee lock to locked position.

In order to insure the sensitivity of the operation, a double air, intake and exhaust check valve is provided for maintaining a predetermined partial vacuum, or a predetermined pressure less than atmospheric in the chamber 3. The partial vacuum holds the socket on the stump.

For the purpose of illustration, assume that pressure to be maintained in the chamber 3 is 13 pounds per square inch, and that the maximum pressure in the chamber permitted to develop under the downward pressure of the stump in the socket is 15 /2 pounds per square inch. The intake of the valve is set to open when the absolute pres sure in the chamber 3 is less than 13 pounds per square inch, and the exhaust, when the pressure under the downward action of the stump in the socket is more than 15 pounds per square inch. In this illustration, a differential of two pounds per square inch operates the diaphragm I. The minimum pressure maintained of 13 /2 pounds per square inch is suiiicient only to hold the socket on the stump without irritation. When the subject applies his Weight to the stump, the air is compressed to 15 pounds per square inch plus, as 15 pounds. The diaphragm is operated against the ambient air pressure to operate the knee lock to locked position. Pressure above the here selected 15 pounds opens the exhaust or the check valving, When the amputee releases the pressure on the stump and; hence, releases the compression in the chamber 3, the intake of the check valve opens if the pressure therein is less than 13 pounds per square inch, maintaining the 2 pound operating differential in pressures.

This double intake and exhaust valveincludes one valve member opening inwardly when the pressure is less than 13 pounds persquare inch, and another opening outwardly when the pressure is above the predetermined maximum, as 15 pounds per square inch.

The double acting check valve here illustrated is of unitary concentric construction and includes a hollow casing 21 threading through an outer circumferential wall of the chamber '3 and having a valve seat 22, a body .3:threading at 2-4 into the casing 2 I, and having a passage therethrough, an axial hub 25 arranged coaxially of the casing and supported from the; body 23,. as by spokes 26, an outer annular valve 2'! normally coacting with the seat 22-and having -a;tubular stem 28 slidable through the-hub 25, a returning spring ZQ'bBtWGEIl the hub 25 which serves as an abutment and the valve 21, the spring tending to hold the outer exhaust valve closed, a second valve 39 opening in the opposite direction from the valve 21 and arranged concentrictherewith and seating at 3! on the valve 27, this inner valve also having a stem 33 extending'through the stem 28 beyond the end .of the same, and a returning spring 34 between an adjustable spring abutment 35 threading on the'end of the stem 33, andanabutment 36 on the end of the tubular stem 28. A suitableclamping nut 31 threads on the casing 2! against the inner wall of the chamber 3 to-secure the casing in position. The abutment-35 serves as a head or knob to open the intake or inner valve 3| when it is desired to break the vacuum in the chamber 3 to remove the socket from the stump.

In operation if normally, or during use of the leg,-the pressure within the chamber 3 develops, in this selected illustration-less than 13 pounds per square inch, the inner valve 30 will open against the action of the spring 34, this occurring when the weight of the amputee isremoved from the socket. Ifhowever, thepressure within the chamber 3 becomes greater thanthe predeterminedselected maximum of 15%;pounds, then the outer valve member 21 will open against the spring 29 and release the excess pressure above pounds.

What I claim is:

1. An artificial leg for above-the-knee amputees including a socket for air tightly fitting the stump of the leg, a lower leg hinged by a knee joint to the socket, a knee lock for braking the hinging movement of the socket and lower leg, the knee lock including an actuating member, a pressure operated movable member closing the lower end of the socket forming a closed air chamber below the end of the stump, and operable by the compressing and releasing of the pressure of the air in the socket by the relative axial action of the stump and the socket when the weight is applied to and released from the stump, and motion transmitting connections between the pressure operated member and the actuating member.

2. An artificial leg for above-the-knee amputees including a socket for air tightly receiving the stump of the leg, and a lower leg hinged.

by a knee joint to the socket, a knee lock for braking the hinging movement of the socket and lower leg, and a control for the knee lock operated by the axial movement of the stump in the socket including a vibratable diaphragm closing the lower end of the socket below the stump and forming a closed air chamber and operable by the compressing and release of the pressure of the air between the stump and the diaphragm, the knee lock including an actuating member, and motion transmitting means between the diaphragm and the actuating member.

3. An artificial leg for above-the-knee amputees including a socket for air-tightly receiving the stump of the leg, and a lower leg hinged by a knee joint to the socket, a knee lock for braking the hinging movement of the socket and the lower leg, a control for the knee lock operated by the axial movement of the stump in the socket, the knee lock including an actuator concentric with and shiftable about the axis of the knee joint to operate and release the knee look, a pressure operating member closing the lower end of the socket forming a closed air chamber below the end of the stump and operable by the compressing and releasing of the pressure of the air by the relative axial action of the stump and the socket, and motion transmitting connections between the pressure operated member and the actuator.

4. An artificial leg for above-the-knee amputees including a socket for air tightly receiving the stump of the leg, and a lower leg hinged by a knee joint to the socket, a knee lock for braking the hinging movement of the socket and the lower leg, a control for the knee lock operated by the axial movement of the stump fitting the socket including a pressure operated member closing the socket below the end of the stump and forming a closed air chamber, and operable by the compressing and releasing of the pressure of the air in the chamber, and spring pressed oppositely acting check valves mounted in the socket and opening into said chamber.

5. An artificial leg for above-the-knee amputees including a socket for air tightly receiving the stump of the leg, and a lower leg hinged by a knee joint to the socket, a knee lock for braking the hinging movement of the socket and the lower leg, a control for the knee lock operated by the axial movement of the stump fitting the socket including a pressure operated member closing the socket below the end of the stump and forming a closed air chamber, and operable by the compressing and releasing of the pressure of the air in the chamber, and an intake and exhaust check valving including an intake valve member operable to open when the pressure in the chamber is less than a predetermined pressure less than atmospheric, and an exhaust valve member operable to open when the pressure in the chamber develops above a predetermined amount greater than atmospheric pressure.

6. In an artificial leg for above-the-knee amputees including a stump receiving socket, a lower leg hinged by a knee joint to the socket, a knee lock for braking the relative hinging movement of the socket and the lower leg, the socket being formed with a closed air chamber below the F portion of the socket in which the stump is located, the chamber having a wall shiftable under differential air pressures in the chamber, motion transmitting connections between said wall and the knee lock, the stump being mounted to 0 have an axial movement in the socket during a walking cycle and thereby vary the air pressure in the air chamber and vary the movement of said wall.

JOHN G. CATRANIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

